"This deal, which delivers on the vote of the (2016) referendum, which brings back control of our money, laws and borders, ends free movement, protects jobs, security and our union -- or leave with no deal, or no Brexit at all."

The announcement of the deal on Tuesday prompted a wave of criticism from eurosceptics in May's Conservative party, as well as her Northern Irish allies, the Democratic Unionist Party (DUP).

"I know that there will be difficult days ahead," May said, adding that intense scrutiny of the agreement was "entirely understandable".

"But the choice was this deal, which enables us to take back control and to build a brighter future for our country, or going back to square one with more division, more uncertainty and a failure to deliver on the referendum."

The prime minister ended on a personal note, saying: "I believe that what I owe to this country is to take decisions that are in the national interest.

"And I firmly believe with my head and my heart, that this is a decision which is in the best interests of our entire United Kingdom."